1. Field of the Invention
The invention relates to a liquid crystal display device and a method of fabricating the same, and more particularly to a light-reflection type liquid crystal display device and a method of fabricating the same
2. Description of the Related Art
Since a portable terminal device such as a portable computer can accumulate power in limited amount, parts constituting a portable terminal device are required to consume small power. Accordingly, not a display unit which can emit light by itself, but a liquid crystal display device which consumes small power is predominantly used as a display unit for a portable terminal device.
However, a liquid crystal display device does not have a function of emitting light by itself, and hence, has to include a light source. In accordance with a light-source, a liquid crystal display device is grouped into a light-reflection type liquid crystal display device, a light-transmission type liquid crystal display device, and a combination type liquid crystal display device.
A light-transmission type liquid crystal display device has a back-light source by which the device can display images.
A light-reflection type liquid crystal display device includes a light-reflector therein, and uses light entering into the device and reflecting at the light-reflector, as a light source. Hence, a light-reflection type liquid crystal display device is not necessary to include a back-light source unlike a light-transmission type liquid crystal display device.
A combination type liquid crystal display device includes a first section fabricated as a light-transmission type liquid crystal display device and a second section fabricated as a light-reflection type liquid crystal display device.
A light-reflection type liquid crystal display device consumes smaller power and can be fabricated thinner and lighter than a light-transmission type liquid crystal display device, and hence, is mainly used as a display unit for a portable terminal device. This is because a light-reflection type liquid crystal display device uses light entering thereinto and reflecting at a light-reflector for displaying images, and hence, is necessary to have a back-light source unlike a light-transmission type liquid crystal display device.
However, since a light-reflection type liquid crystal display device uses external light as a light source, it is difficult or almost impossible for a user to clearly see displayed images, if it is dark around the device.
In order to solve such a problem, a light-reflection type liquid crystal display device designed to include a preliminary light source which supplies light to the device through a light-guide has been suggested, for instance, in Japanese Patent No. 2699853 (Japanese Patent Application Publication No. 7-199184), and Japanese Patent Application Publications Nos. 11-149252, 11-219610 and 2000-147499.
FIG. 1 is a cross-sectional view of an example of a conventional light-reflection type liquid crystal display device including a preliminary light source.
A light-reflection type liquid crystal display device 100 illustrated in FIG. 1 is comprised of a liquid crystal display panel 101, a polarizer 102 lying on the liquid crystal display panel 101 in such a direction as facing a viewer, a light-guide 103 mounted on the polarizer 102, a resin layer 104 sandwiched between the polarizer 102 and the light-guide 103 for fixing them to each other, and a light source 105 located adjacent to an end of the light-guide 103, and supplying light to the liquid crystal display panel 101 through the light-guide 103. Though not illustrated, the light source 105 is usually surrounded by a cover (see FIG. 4C).
Light emitted from the light source 105 reaches the polarizer 102 through the light-guide 103, is polarized when passing through the polarizer 102, and reaches the liquid crystal display panel 101 to thereby be used for displaying images.
FIGS. 2A to 2D are cross-sectional views of the light-reflection type liquid crystal display device 100 illustrated in FIG. 1, illustrating respective steps of a method of fabricating the same.
First, as illustrated in FIG. 2A the polarizer 102 is mounted on the liquid crystal display panel 101, and then, liquid acrylic resin 104 which will be hardened when ultra-violet ray is irradiated thereto is dropped onto the polarizer 102.
Then, as illustrated in FIG. 2B, the light-guide 103 is mounted onto the polarizer 102. The resin 104 spreads wholly on the polarizer 102 due to a weight of the light-guide 103.
While the resin 104 is being extended, the light-guide 103 is positioned relative to the liquid crystal display panel 101, as illustrated in FIG. 2C.
Then, as illustrated in FIG. 2D, ultra-violet (UV) ray from which short-wave ultra-violet is cut is irradiated to the resin 104 through a glass filter 106 to thereby harden the resin 104.
Thus, the light-reflection type liquid crystal display device 100 illustrated in FIG. 1 is completed.
However, the above-mentioned method of fabricating the light-reflection type liquid crystal display device 100 is accompanied with the following problems.
The first problem is that a relative position and/or angle between the liquid crystal display panel 101 and the light-guide 103 is deviated from a desired position or angle while the resin 104 is being extended.
As a result, it is necessary to adjust the relative position before ultra-violet ray is irradiated to the resin 104, causing an increase in the number of fabrication steps and a time necessary for fabricating the liquid crystal display device 100.
The second problem is that, as illustrated in FIG. 3, the resin 104 often spreads beyond the polarizer 102 and covers the liquid crystal display panel 101 therewith.
The light-guide 103 and the polarizer 102 are generally composed of plastic. The resin 104 is selected among resin having a linear expansion coefficient close to that of the light-guide 103 and the polarizer 102, for instance, a linear expansion coefficient in the range of 3×10−5 to 7×10−5/degree. However, if the resin 104 spreads onto the liquid crystal display panel 101 as illustrated in FIG. 3, the resin 104 might be deformed at high or low temperature due to a difference in a linear expansion coefficient between the resin 104 and the liquid crystal display panel 101 composed of glass having a linear expansion coefficient of 5×10−6/degree. As a result, the resin 104 might be peeled off at a portion at which the resin 104 is deformed.